The number of size are etching into the Feeler Gauges for easy identification The Feeler Gauges doesn ' t get rusty and easy to open Tapered Feeler Gauges set is steel, hardened and polishing for long time and accurate usage Feeler gauges for valves can fold into steel case with a thumbscrew, easy to carry, to take and safe to store The edges of the Feeler Gauges set is steel and polishing It ' s full of bright metal texture specially treated, smooth and doesn ' t hurt your hand, Manufacturer: LiRRvb